In general, as life-saving means to cope with safety accidents that occur in swimming, a life vest is a safety item to be worn by people in swimming or by rescue workers for safety.
Further, the life vests are indispensably equipped in vessels cruising on rivers or seas.
Such life vests have a basic function of lifting a human body above the water surface in water activities, and an additional function of protecting the human body from hypothermia and an external impact as well.